He is talking about people self-hosting GitLab (so they aren't paying monthly fees to GitLab), and comparing the Engineering hours + server uptime costs + related costs to just paying for GitHub (which is cheaper).
The "no costs" is a wild argument to me though, because I've seen "we want it locally available" and "we can't put code in the cloud/"laws"" etc, but never "this is cheaper than a couple bucks per month"